The remarkable ability of geckos to climb and run rapidly on walls and ceilings has recently received considerable interest from many researchers.Significant progress has been made in understanding the attachment and ...The remarkable ability of geckos to climb and run rapidly on walls and ceilings has recently received considerable interest from many researchers.Significant progress has been made in understanding the attachment and detachment mechanisms and the fabrication of articulated gecko-inspired adhesives and structured surfaces.This article reviews the direct experiments that have investigated the properties of gecko hierarchical structures,i.e.,the feet,toes,setae,and spatulae,and the corresponding models to ascertain the mechanical principles involved.Included in this review are reports on gecko-inspired surfaces and structures with strong adhesion forces,high ratios of adhesion and friction forces,anisotropic hierarchical structures that give rise to directional adhesion and friction,and“intelligent”attachment and detachment motions.展开更多
Neurosurgery is a highly specialized field:it often involves surgical manipulation of noble structures and cerebral retraction is frequently necessary to reach deep-seated brain lesions.There are still no reliable met...Neurosurgery is a highly specialized field:it often involves surgical manipulation of noble structures and cerebral retraction is frequently necessary to reach deep-seated brain lesions.There are still no reliable methods preventing possible retraction complications.The objective of this study was to design work chambers well suited for transcranial endoscopic surgery while providing safe retraction of the surrounding brain tissue.The chamber is designed to be inserted close to the intracranial point of interest;once it is best placed it can be opened.This should guarantee an appreciable workspace similar to that of current neurosurgical procedures.The experimental aspect of this study involved the use of a force sensor to evaluate the pressures exerted on the brain tissue during the retraction phase.Following pterional craniotomy,pressure measurements were made during retraction with the use of a conventional metal spatula with different inclinations.Note that,although the force values necessary for retraction and exerted on the spatula by the neurosurgeon are the same,the local pressure exerted on the parenchyma at the edge of the spatula at different inclinations varied greatly.A new method of cerebral retraction using a chamber retractor(CR)has been designed to avoid any type of complication due to spatula edge overpressures and to maintain acceptable pressure values exerted on the parenchyma.展开更多
基金the Natural Science Foundation of China(Grant Nos.51175281 and 51021064)。
文摘The remarkable ability of geckos to climb and run rapidly on walls and ceilings has recently received considerable interest from many researchers.Significant progress has been made in understanding the attachment and detachment mechanisms and the fabrication of articulated gecko-inspired adhesives and structured surfaces.This article reviews the direct experiments that have investigated the properties of gecko hierarchical structures,i.e.,the feet,toes,setae,and spatulae,and the corresponding models to ascertain the mechanical principles involved.Included in this review are reports on gecko-inspired surfaces and structures with strong adhesion forces,high ratios of adhesion and friction forces,anisotropic hierarchical structures that give rise to directional adhesion and friction,and“intelligent”attachment and detachment motions.
文摘Neurosurgery is a highly specialized field:it often involves surgical manipulation of noble structures and cerebral retraction is frequently necessary to reach deep-seated brain lesions.There are still no reliable methods preventing possible retraction complications.The objective of this study was to design work chambers well suited for transcranial endoscopic surgery while providing safe retraction of the surrounding brain tissue.The chamber is designed to be inserted close to the intracranial point of interest;once it is best placed it can be opened.This should guarantee an appreciable workspace similar to that of current neurosurgical procedures.The experimental aspect of this study involved the use of a force sensor to evaluate the pressures exerted on the brain tissue during the retraction phase.Following pterional craniotomy,pressure measurements were made during retraction with the use of a conventional metal spatula with different inclinations.Note that,although the force values necessary for retraction and exerted on the spatula by the neurosurgeon are the same,the local pressure exerted on the parenchyma at the edge of the spatula at different inclinations varied greatly.A new method of cerebral retraction using a chamber retractor(CR)has been designed to avoid any type of complication due to spatula edge overpressures and to maintain acceptable pressure values exerted on the parenchyma.
